Lithium-ion battery 18V 9000 Mah compatible with Makita BL1815, BL1820, BL1830, BL1840, BL1850, BL1860 - AliExpress
Amazon.com: LeWattgend Rechargeable 9V Lithium Batteries, 9V 1000mAh(9000 mWh) Long Lasting Rechargeable Batteries USB C 1000 Cycles Charge for Smoke Detector Quick Charge in 2 Hours : Health & Household